Interface characterization of thermoplastic skin-stiffener composite manufactured using laser-assisted tape placement

Laser-Assisted Tape Placement (LATP) is an advanced manufacturing process which has gained the attention of the aerospace industry. Composite laminates manufactured using this technique have to be characterized effectively to assess their suitability for use in structural applications. A representative skin and stiffener test coupon was manufactured using the LATP method from carbon fiber (CF) reinforced polyether ether ketone (PEEK) tapes. The main objective was to characterize the interaction between skin and stiffener in terms of interlaminar shear strength (ILSS) and fracture toughness (mode-I and mode-II) properties. For initial ILSS tests, non-unidirectional stacking sequences were used for skin and stiffener to ensure failure at their interface. Further, ILSS, double cantilever beam (DCB) and end-notched flexure (ENF) fracture toughness tests were carried out on unidirectional (UD) skin-stiffener laminates. All the mechanical tests were carried out as per ASTM standards. The values of ILSS and fracture toughness in mode-I and mode-II were comparable with the reported results stating the competence of the LATP manufactured CF/PEEK skin-stiffener.